<?php

/**
 * Chainable filters for custom URI processing.
 * 
 * These filters can perform custom actions on a URI filter object,
 * including transformation or blacklisting.
 * 
 * @warning This filter is called before scheme object validation occurs.
 *          Make sure, if you require a specific scheme object, you
 *          you check that it exists. This allows filters to convert
 *          proprietary URI schemes into regular ones.
 */
class HTMLPurifier_URIFilter
{
    
    /**
     * Unique identifier of filter
     */
    var $name;
    
    /**
     * Performs initialization for the filter
     */
    function prepare($config) {}
    
    /**
     * Filter a URI object
     * @param &$uri Reference to URI object
     * @param $config Instance of HTMLPurifier_Config
     * @param &$context Instance of HTMLPurifier_Context
     * @return bool Whether or not to continue processing: false indicates
     *         URL is no good, true indicates continue processing. Note that
     *         all changes are committed directly on the URI object
     */
    function filter(&$uri, $config, &$context) {
        trigger_error('Cannot call abstract function', E_USER_ERROR);
    }
    
}
